For studying the mechanical performance of CFST columns under lateral impact loading, transverse drop impact tests on CFST columns with circular cross-section under impact loading were carried out to obtain the failure mode, global deformation and strain distribution characteristics. The characteristics of impact force and time history curve of midspan deflection were analyzed. Also, the influences of parameters, such as strength of steel and concrete, on the mechanical behavior of CFST columns with circular cross-section were studied using ABAQUS software. The results show that within the scope of the test, with the increment of impact energy, the peak values of impact force, midspan deflection and duration of impact increase; with the increment of steel ratio, the peak and platform values of impact force become greater, but the peak value of midspan deflection and duration of impact get smaller; the yield strength of steel has great influence on the impact resistance of specimens, while the concrete compressive strength has relatively small influence. © 2017, Editorial Office of Journal of Building Structures. All right reserved.